UV water disinfector

ABSTRACT

A device that permits the in-home UV treatment of drinking water such as tap water is disclosed. The device employs a bare low-energy UV lamp suspended below a reflector and above a free surface of water flowing within the device. The water is supplied from a tap or other store of drinking water and proceeds through the device by the force of gravity. The device itself is not pressurized. The flow of water within the device is exposed to UV radiation from the UV lamp and is disinfected as a result. In the illustrated embodiment, the device is of a small size to permit its use, for example, directly at a tap for drinking water within the home. The flow rate of the device is commensurate with the normal flow rate of tap water, preferably less than about 8 liters per minute. The lamp power for safely disinfecting the water can be less than 20 watts, and in the illustrated embodiment the lamp is a low-pressure Hg lamp.

REFERENCE TO RELATED APPLICATION

This application is a continuation of co-pending U.S. application Ser.No. 10/043,647, filed Jan. 10, 2002, which claims the priority benefitunder 35 U.S.C. § 119(e) to provisional application No. 60/261,120,filed Jan. 11, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to the UV disinfection of water andother liquid streams. In particular, the present invention provides a UVdisinfector for use in the disinfection of tap water and other sourcesof drinking water used in the home.

2. Description of the Related Art

Methods used heretofore to disinfect water include the use of chlorineand other chemical agents as well as irradiation. However, certainpathogenic organisms, such as Cryptosporidium parvum, are resistant tochemical-based disinfection. Additionally, organisms such asCryptosporidium, which is present in most municipal drinking watersystems, have recently been shown to present a significant health riskto immunocompromised individuals even at the very low levels at whichsuch pathogens are present in municipal drinking water.

SUMMARY OF THE INVENTION

The UV water disinfector of the present invention provides a simplesolution to the problems described above in that it is a device thatpermits the in-home UV treatment of drinking water such as tap water.The device of the preferred embodiment employs a bare low-energy UV lampsuspended above a free surface of water flowing within the device. Thewater is supplied from a tap or other store of drinking water andproceeds through the device by the force of gravity. The device itselfis not pressurized. The flow of water within the device is exposed to UVradiation from the UV lamp and is disinfected as a result.

In the illustrated embodiment, the device is of a small size to permitits use, for example, directly at a tap for drinking water within thehome. The flow rate of the device is commensurate with the normal flowrate of tap water, preferably less than about 8 liters per minute. Thelamp power for safely disinfecting the water can be less than 20 watts,and in the illustrated embodiment the lamp is a low-pressure Hg lamp.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view depicting the UV disinfector ofan embodiment of the present invention.

FIG. 2 is a side cross-sectional view of the UV disinfector of the sameembodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 depicts a UV water disinfector 1 in accordance with an embodimentof the present invention. A main water tray 73, inlet manifold 21, andupper reflector 51 are shown in FIG. 1. The water disinfector 1 alsoincludes an outer casing (not shown). The disinfector 1 includes manyfeatures and advantages generally described in U.S. Pat. No. 5,780,860,issued Jul. 14, 1998, the disclosure of which is incorporated herein byreference. However, the disinfector 1 is particularly adapted (e.g., insize, power, flow rate, etc.) to use in the home for disinfectingmunicipal water that is generally considered safer for drinking. Forexample, the portions of water disinfector 1 shown in FIG. 1 preferablyhave a length of about 48 cm or less, a width of about 19.5 cm or less,and a height of about 15.75 cm or less; more preferably have a length ofabout 40 cm or less, a width of about 16.25 cm or less, and a height ofabout 13.125 cm or less; even more preferably have an overall lengthwithin a range of about 35.2-28.8 cm, a width within a range of about14.3-11.7 cm, and a height within a range of about 11.55-9.45 cm; andmost preferably have an overall length of approximately 32 cm, a widthof about 13 cm, and a height of about 10.5 cm. Such a small size is welladapted to in-home use, such as in a kitchen sink or a counter adjacentthereto.

Furthermore, unlike many prior art devices, the UV water disinfector 1in accordance with the present embodiment is not pressurized andinvolves no pumping of the water as it is being treated. The waterpasses through the treatment chamber as a result of gravity.

Referring to FIGS. 1 and 2, an inlet port 11 that is adapted to beconnected to a common household tap, or a holding tank fed by tap water,protrudes into an inlet chamber 31. The feed water enters the UVdisinfector 1 through the inlet port 11 by the pressure from the tap.The inlet port 11 enters an inlet manifold 21, which is comprised of avertical inlet feed tube 23 which connects to a horizontal inletdistribution tube 25, both of which have a diameter of approximately 1.5cm and which comprise food-grade plastic such as polypropylene. Thus,the inlet manifold 21 forms an inverted T configuration. The inlet feedtube 23 enters the UV disinfector 1 from above. As an option, a solenoidshut off valve can be provided in the inlet feed tube 23. The solenoidvalve will stop the flow of feed water into the UV disinfector if thereis a stoppage of power to the UV disinfector, as described in U.S. Pat.No. 5,780,860.

The bulk of the inlet manifold 21 is positioned in the inlet chamber 31.The inlet chamber 31 is defined by a main tray inlet wall 33 (about 9 cmby 5 cm), a main tray floor 35, and a baffle wall 37 (about 9 cm by 5cm). There is about a 6 cm separation between the main tray inlet wall33 and the baffle wall 37. The inlet feed tube 23 typically abuts thebaffle wall 37. The inlet distribution tube 25 typically rests directlyon the sides of main tray floor 35, providing for considerablestability. Additionally, the inlet distribution tube 25 can be attachedto the baffle wall 37 by ring attachments 39. The distribution tube 25is provided with distribution tube holes 41, which provide aflow-through of feed water into inlet chamber 31. These distributiontube holes 41 are typically 5 mm in diameter and are spaced at intervalsof 1 cm from the center of one hole to the center of the neighboringhole. In addition, although not depicted in the Figures, a smaller holehaving a diameter of approximately 2 mm is provided at the opposite sideof distribution tube 25 from the distribution tube holes 41 and centeredso as to be aligned with the vertical inlet feed tube 23. This holeserves to reduce the turbulence of the water flow into the inlet chamber31.

The regulation of the water flow entering the UV disinfector 1 isprovided by adapting the inlet port 11 to the type of tap employed. If,however, too much water should enter inlet chamber 31, the main trayinlet wall 33 is provided with a notch 390 so that feed water willoverflow this wall rather than overflowing the baffle wall 37. The lowpoint of the notch 390 is thus below the height of the baffle wall 37and in the illustrated embodiment is approximately 3.4 cm above the maintray floor 35. This excess feed water falls to an outer casing bottom(not shown), where it drains away through a gap.

A treatment chamber 47 is defined by the baffle wall 37, the main trayfloor 35, a curved outlet baffle dam 49, and a top reflector 51. Wheninstalled, the top reflector 51 overlaps the main tray by approximately5 mm. The top reflector 51 houses a UV lamp 53 that is seated in asocket 54. The socket 54, in turn, is attached to the top reflector 51by socket attachment bolts. Thus, the top reflector 51 supports andsuspends the UV lamp 53 above the treatment chamber 47.

A power source and shut off relay provide the power to UV lamp 53through a lamp circuit and ballast (not shown). The power source andshut off relay can be additionally connected to a solenoid shutoffvalve, as mentioned.

The main tray floor 35 rests directly on an outer casing base that isnot depicted in the Figures. The main tray floor 35 is angled to directthe laminar flow of the feed water that is produced by the baffle wall37. The main tray is constructed of stainless steel having a UVreflectance of approximately 30%, while the top reflector is constructedof polished aluminum, having a UV reflectance in a range ofapproximately 75-80%.

In operation, the top reflector 51 recaptures otherwise lost UV lightfrom the top of UV lamp 53, directing it back to the laminar flow. Thefeed water traverses the treatment chamber 47, and then cascades overoutlet baffle dam 49, after which it is collected by a suitablecollection device (not shown) for use as drinking water. Working inconcert, these various features of the treatment chamber 47 ensure thatthe feed water directed in the laminar flow typically receives a similardosage of UV radiation wherever it is positioned in the treatmentchamber 47. This dosage is preferably within a range of 110-150 mJ/cm²,more preferably within a range of 115-125 mJ/cm², and most preferablyapproximately 120 mJ/cm² under ideal conditions (water with turbidity ofless than 1 NTU and a UV transmittance of more than 95% at 1 cm).

A suitable outlet box or other device such as a tap or the like, notdepicted in the Figures, receives the treated water as it cascades overthe outlet baffle dam 49, the top of which is approximately 3 cm abovethe main tray floor 35.

The UV lamp preferably consumes 25 watts or less, more preferably about20 watts or less, even more preferably about 8-15 watts, and mostpreferably about 9-10 watts. This is considerably less power than thatconsumed by conventional water treatment devices. In other arrangements,the UV lamp may be a medium pressure lamp, which outputs broadband UVradiation, which is defined herein as UV radiation exhibiting a broadpeak centered at about 500 nm, with the spectrum ranging from 250 nm to800 nm. U.S. Pat. No. 6,129,893 to Bolton et al. discloses that suchbroadband UV radiation is capable of preventing replication inCryptosporidium parvum. In the preferred embodiment, however, the lampis a low pressure lamp, which outputs narrow-band UV radiation, which isdefined herein as UV radiation exhibiting a narrow peak centered at253.7 nm, with the width at one-half maximum intensity of less than 1 nmon either side of the center at 253.7 nm.

The use of narrow-band UV radiation has been shown by the presentinventors to inactivate Cryptosporidium parvum oocysts, as described inDrescher et al., “Cryptosporidium Inactivation by Low Pressure UV in aWater Disinfection Device,” Journal of Environmental Health, Vol. 64,No. 3, pp. 31-35 (October 2001), the disclosure of which is incorporatedherein in its entirety. In brief, the inventors determined that whenwater containing a high level of live oocysts of Cryptosporidium parvum(which is one of the pathogens posing a health risk to immunocompromisedindividuals) was irradiated with narrow-band UV at a dosage of 120mJ/cm², mice which ingested the treated water showed no signs ofinfection by the pathogen one week after ingestion. The infectivity ofthe oocysts was reduced by at least 5.4 orders of magnitude as a resultof the narrow-band UV treatment. It is thus apparent that thisnarrow-band UV treatment is highly effective in the inactivation ofthese pathogens.

Prior art quartz sleeve protectors for UV lamp 53 are eliminated in thepresent design because the UV lamp 53 is carefully air-suspended abovethe flow of the feed water, and also because the UV lamp 53 burns at asufficient temperature that condensation never develops at its surface.Both the failure of moisture requirements and the heavy UV bombardmentavoids the problems of biomass buildup which plagued prior artconfigurations.

The baffle wall 37 rises from the main tray floor 35 extending along themain tray walls 75 upwards to the top edge thereof. The baffle wall 37serves to position the feed water so as to provide a narrow distributionof UV dosages. However, the baffle wall 37 does not limit the height ofthe feed water. The height of the feed water as it traverses the UVdisinfector 1 is limited to the height of the main tray walls 75.

The ultimate regulator of the feed water level during processing in UVdisinfector 1 is outlet baffle dam 49, which rises only partway to thetop of the main tray walls 75. The main tray unit 73 is made about 2 cmsmaller than the outer casing (not depicted in the Figures), so there isconsiderable room for overflow to escape the main tray 73.

In the perspective view of FIG. 1, it can be seen that the baffle wall37 is provided with baffle wall holes 64 about 0.3 cm in diameter, andspaced evenly about 0.6 cm apart from center to center. These serve tolaminarize the flow of the feed water into treatment chamber 47 as shownin FIGS. 1 and 2.

It should be noted that these baffle wall holes 64, along with the small2 mm hole in the intake manifold 21, are preferably the smallest holesthrough which the feed water passes in the disinfector of the presentembodiment; no upstream or downstream filters are provided. Thisarrangement allows a flow rate appropriate for a household tap to bemaintained even though the disinfector as a whole is quite small. Inother arrangements, upstream or downstream filters may also be provided.

The gravity-driven feed rate of the water through treatment chamber 47is preferably 8 liters per minute or less, more preferably about 4liters per minute or less, even more preferably within a range of about1-3 liters per minute, and most preferably approximately about 2 litersper minute.

The UV water disinfector described above is used in the followingmanner. First, the inlet port 11 is connected to a household tap, andpower is supplied to the UV lamp. Next, the tap is opened, and waterenters the inlet manifold 21 as a result of the tap pressure, passesthrough the holes provided in the inlet manifold 21, and enters inletchamber 31. Next, this water is channeled in a laminar flow through thebaffle wall holes 64 and enters treatment chamber 47, where it issubjected to a dose of UV sufficient to inactivate pathogenic organismsand disinfect the water. Finally, the disinfected water passes overoutlet baffle dam 49 and is collected by a suitable collection devicefor use as drinking water.

Although the forgoing invention has been described in terms of a certainpreferred embodiment, other embodiments will become apparent to those ofordinary skill in the art in view of the disclosure herein. Accordingly,the present invention is not intended to be limited by the recitation ofpreferred embodiments, but is intended to be defined solely by referenceto the appended claims.

1. An ultraviolet (UV) water disinfector, comprising: a feed waterdelivery system, wherein the feed water delivery system is adapted toconnect to a holding tank, an inlet chamber housing at least a portionof the feed water delivery system, a baffle wall downstream of the feedwater delivery system, the baffle wall having a plurality of spacedperforations, an air-suspended UV lamp capable of providing narrowbandUV radiation sufficient to inactivate Cryptosporidium parvum oocysts,and a treatment chamber beneath the UV lamp downstream of the bafflewall, wherein water is driven by gravity at a flow rate of 8 liters perminute or less.
 2. The UV water disinfector of claim 1, furthercomprising a notch in said inlet chamber adapted to allow excess waterto overflow, and an outer shell adapted to collect water whichoverflows.
 3. The UV water disinfector of claim 1, wherein the UV lampis adapted to provide narrowband UV radiation at a dosage of about 120mJ/cm².
 4. The UV water disinfector of claim 3, wherein the UV lamp usesless than 25 watts of power.
 5. The UV water disinfector of claim 4,wherein the UV lamp uses less than about 20 watts of power.
 6. The UVwater disinfector of claim 5, wherein the UV lamp uses about 8-15 wattsof power.
 7. The UV water disinfector of claim 1, wherein the feed waterdelivery system has a flow rate of about 4 liters per minute or less. 8.The UV water disinfector of claim 1, wherein the feed water deliverysystem has a flow rate within a range of about 1-3 liters per minute. 9.The UV water disinfector of claim 1, having a length of about 48 cm orless, a width of about 19.5 cm or less, and a height of about 15.75 cmor less.
 10. The UV water disinfector of claim 1, having a length of 40cm or less, a width of 16.25 cm or less, and a height of 13.125 cm orless.
 11. The UV water disinfector of claim 1, having a length within arange of about 35.2-28.8 cm, a width within a range of about 14.3-11.7cm, and a height within a range of about 11.55-9.45 cm.
 12. Anultraviolet (UV) water disinfector, comprising: a feed water deliverysystem, wherein the feed water delivery system is configured to receivewater from a holding tank, an inlet chamber housing at least a portionof the feed water delivery system, a baffle wall downstream of the feedwater delivery system, the baffle wall having a plurality of spacedperforations, an air-suspended UV lamp using 20 watts of power or less,the UV lamp capable of providing narrowband UV radiation sufficient toinactivate Cryptosporidium parvum oocysts, and a treatment chamberbeneath the UV lamp downstream of the baffle wall, wherein the feedwater delivery system and the treatment chamber are configured todeliver water, under the influence of gravity, at a rate of less thanabout 8 liters per minute.
 13. The UV water disinfector of claim 12,wherein the UV lamp comprises a low pressure mercury lamp.
 14. The UVdisinfector of claim 12, having a length of about 40 cm or less, a widthof about 16.25 cm or less and a height of about 13.125 cm or less.
 15. Amethod of disinfecting household tap water in a UV water disinfector,comprising: delivering household tap water to a feed water deliverysystem, flowing the household tap water from the feed water deliverysystem into a treatment chamber, wherein the water flowing into thetreatment chamber is driven by gravity at a flow rate of 8 liters perminute or less, and disinfecting the household tap water by providingnarrowband UV radiation from an air-suspended UV lamp over the treatmentchamber, wherein the narrowband UV radiation is sufficient to inactivateCryptosporidium parvum oocysts.
 16. The method claim 15, wherein the UVlamp uses less than 25 watts of power.
 17. The method of claim 15,wherein the UV water disinfector has a length of about 48 cm or less, awidth of about 19.5 cm or less, and a height of about 15.75 cm or less.18. The method of claim 15, wherein the UV lamp comprises a low pressuremercury lamp.
 19. The method of claim 15, wherein the feed waterdelivery system is adapted to connect to a household tap.
 20. The methodof claim 15, wherein the feed water delivery system is adapted toconnect to a holding tank.